Hydrogenation and annealing kinetics of group-III acceptors in oxidized silicon exposed to keV electrons

Abstract

Group-III acceptors are deactivated by hydrogen released by 8 keV electrons in metal-oxide-silicon capacitors. The decay of the acceptor density during keV electron beam irradiation shows three conjoined phases: an initial delay, a short-time transient, and a long-time transient. This overlapping temporal characteristic is related to comparable rates of hydrogen bond breaking at the gate–oxide interface, hydrogen migration across the oxide, and emission and capture of proton at the group-III acceptor. Isothermal annealing data showed clearly two distinct annealing phases: an initial exponential rise and the long-time second-order recovery kinetics. The hydrogenation and annealing rate coefficients from these electron beam irradiated oxides are different from those obtained from avalanche electron injection (AEI) experiments. The difference suggests that the atomic structure surrounding the hydrogen-acceptor complex depends on the hydrogenation energetics. Compared with those electrons in the AEI experiments (tens eV), the higher-energy (keV) electrons can create more extended interfacial dangling bonds which are hydrogen or proton traps.